It was bound to happen but the game has reached status that many popular games only wish for in its short time. But don't count it out just yet, this is only Gen 1 and Gamefreak made sure to say during E3 that generations will be a thing. While it probably won't retain its success because of course, it requires more effort that simply sitting on a couch and pressing a screen, which people really don't willingly do.
As a Nintendo and Pokemon fan, I'm pleased with the games performance and I'm sure it'll last a long time but I'm more interested in Nintendo's traditional content.